8.12D: Nitrospirae and Deferribacter

Nitrospirae is a phylum of bacteria containing only one class: Nitrospira, which itself contains one order: Nitrospirales, and one family: Nitrospiraceae. However, it includes multiple genera, the largest of which is Nitrospira. The first member of this phylum, Nitrospira marina, was discovered in 1986 by Watson et al., isolated from the Gulf of Maine. The second member of this phylum, Thermodesulfovibrio yellowstonii, was discovered in 1994. The third, Nitrospira moscoviensis, was discovered in 1995 from a corroded iron pipe in a Moscow heating system. It is a Gram-negative nitrite-oxidizing organism with a helical to vibroid morphology 0.9-2.2 x 0.2-0.4 micrometers in size.

Some nitrospirae species perform important functions in the Nitrogen Cycle. The Nitrogen Cycle describes the changes in nitrogenous compounds in the environment. Because many of them are toxic, it is important to know something about this cycle. Luckily, these compounds are converted to less and less toxic forms through this Nitrogen Cycle.

Figure: Nitrogen cycle in aquarium: Legend: (1) Addition of food and nutrients, (2) Production of urea and ammonia by fish, (3) Ammonia is converted to nitrites by beneficial nitrosomonas bacteria, (4) Nitrites are converted to nitrates by beneficial nitrospira bacteria. Less toxic nitrates are removed by plants and periodic water changes. (5) Evaporation. (6) Light. (7) Soil. (8) O2 produced by plants. (9) CO2 produced by fish.

To simplify, if you start with your organisms, they release a compound, ammonia, as a waste product or a product of decomposition. Ammonia is both quite toxic and dangerous. By a process known as nitrification, bacteria convert these waste products to less toxic forms. These bacteria live in aerobic conditions and benefit from the presence of oxygen. First the ammonia is converted to nitrites by Nitrosomonas; this compound is still toxic. Next, nitrites are converted to nitrates by Nitrobacter or Nitrospira. Nitrates are much less toxic compared to ammonia and nitrite. In an environment with a healthy colony of these nitrifying bacteria, ammonia and nitrites levels will reach zero.

Deferribacter is a genus in the phylum Deferribacteres (Bacteria).The genus contains 4 species:

D. abyssi

D. autotrophicus

D. desulfuricans

D. thermophilus

Key Points

Nitrospirae is a phylum of bacteria. It contains only one class, (Nitrospira), which itself contains one order (Nitrospirales), and one family (Nitrospiraceae). It includes multiple genera, such as Nitrospira, the largest. The first member of this phylum, Nitrospira marina, was discovered in 1985.

Nitrospira is a genus of bacteria in the phylum Nitrospirae. The second member of this genus was discovered in 1995 from a corroded iron pipe in a Moscow heating system.

In the nitrogen cycle, nitrites are converted to nitrates by Nitrobacter or Nitrospira.

Deferribacter is a genus in the phylum Deferribacteres (Bacteria).The genus contains 4 species.

Key Terms

nitrogen cycle: The natural circulation of nitrogen, in which atmospheric nitrogen is converted to nitrogen oxides by lightning and deposited in the soil by rain where it is assimilated by plants and either eaten by animals (and returned as feces) or decomposed back to elemental nitrogen by bacteria.

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